Abstract: A releasable security fixing system comprising a bolt (3) having a head and a shank. A security nut (7) which is engageable threadingly with the shank of the bolt and a cupped collar (5) having a hole in the cupped end to fit over the shank of the bolt and having a length greater than the projecting end of the shank of the bolt when installed, and being open at the other end to receive the security nut. The security nut has a circular periphery and is provided with a plurality of grooves (77) cut into one end of the nut and extending away from said end. A complimentary key (10) is provided for fitting and releasing the nut. The shank of the bolt is such that, in use, the shank of the bolt projects beyond the security nut in its installed position, and the key having an aperture to receive the projecting end of the bolt shank.

Abstract: A releasable security fixing system comprising a bolt (3) having a head and a shank. A security nut (7) which is engageable threadingly with the shank of the bolt and a cupped collar (5) having a hole in the cupped end to fit over the shank of the bolt and having a length greater than the projecting end of the shank of the bolt when installed, and being open at the other end to receive the security nut. The security nut has a circular periphery and is provided with a plurality of grooves (77) cut into one end of the nut and extending away from said end. A complimentary key (10) is provided for fitting and releasing the nut. The shank of the bolt is such that, in use, the shank of the bolt projects beyond the security nut in its installed position, and the key having an aperture to receive the projecting end of the bolt shank.